The present invention is directed to biodegradable aliphatic-aromatic copolyester films. More particularly, the present invention is directed to biodegradable aliphatic aromatic copolyester films suitable for use in absorbent articles that contain an outer cover made from the film material. When filled with a filler material such as calcium carbonate, the aliphatic-aromatic copolyester films have high vapor permeability and good barrier and tensile strength properties.
People rely on disposable absorbent articles, such as diapers, to make their lives easier. Diapers commercially available today are generally comfortable to the wearer, and provide a good barrier against leakage out of the diaper. Despite providing good barrier properties against liquids, many commercially available diapers allow water vapor to pass through the diaper and into the environment to lessen the amount of moisture held against the skin and reduce the chance of skin irritation and rash due to skin overhydration. In order to allow the passage of vapor through the diaper and into the environment while holding liquid, many diapers comprise a laminated outer cover, often referred to as a breathable outer cover.
Generally, this breathable outer cover is comprised of a non-woven outer-facing layer joined to an inner-facing linear low density polyethylene layer. The polyethylene layer will typically comprise calcium carbonate, which causes a series of openings to develop in the polyethylene layer when the film is stretched prior to use in the product, which ultimately allows water vapor to pass through without allowing liquid to pass through.
Although most commercially available diapers today comprise an outer cover suitable for achieving the goals outlined above, one shortcoming to date has been that the polyethylene used in the manufacturing of the diaper, and specifically one layer of the outer cover, is not substantially biodegradable. Because of the popularity of diapers and other absorbent products and the large number of these products that are utilized each year, it could be beneficial to provide absorbent article components that exhibit improved biodegradability in landfills after use and disposal.